1. Technical Field
The present invention relates to a piezoelectric device, a liquid ejecting head and a liquid ejecting apparatus.
2. Related Art
A representative example of a liquid ejecting head that ejects liquid droplets includes an ink jet recording head that ejects ink droplets. As the ink jet recording head, for example, there is known a device that includes a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is formed, and a piezoelectric element disposed on one side of the flow path forming substrate, and in which ink droplets are ejected from the nozzle opening by causing a pressure change in ink in the pressure generating chamber by a piezoelectric element.
A wiring substrate is disposed so as to face the flow path forming substrate, and wiring disposed on the wiring substrate is connected to each of the piezoelectric elements. Specifically, the piezoelectric element includes an individual electrode individually disposed for each of active portions and a common electrode commonly disposed for a plurality of active portions, a driving signal is supplied to the individual electrode, and a bias voltage (vbs) is supplied to the common electrode (for example, refer to JP-A-2012-171149).
In a configuration having a plurality of piezoelectric element rows in which the piezoelectric elements are arranged in parallel in one direction, a supply wiring commonly connected to the common electrode of the piezoelectric element row is provided. That is, the bias voltage is supplied to a common electrode of a plurality of piezoelectric element rows by one supply wiring. An auxiliary wiring is connected to the supply wiring. By the auxiliary wiring, it is possible to lower an electric resistance value of the supply wiring.
The bias voltage applied to a common electrode of each of piezoelectric element rows is supplied by a common supply wiring in the piezoelectric element rows. In such a configuration, there is a possibility that a so-called electric crosstalk in which a change occurs in the drive of the other piezoelectric element row, in particular the power supply, depending on the number of piezoelectric elements driven simultaneously in one piezoelectric element row. Although an auxiliary wiring is connected to the supply wiring, this auxiliary wiring is also common to the piezoelectric element row. Therefore, there is a possibility that electric crosstalk may occur even by the auxiliary wiring. Due to the occurrence of the electric crosstalk, there is a problem in that variation in ejection characteristics of the ink droplets ejected by the piezoelectric element corresponding to the other piezoelectric element row, in particular, in a flight speed of the ink droplets, and in a size of the ink droplets occurs.
In a case where the auxiliary wiring is disposed on the surface of a wiring substrate on a flow path forming substrate side, as a result of forming the auxiliary wiring so as to satisfy a necessary resistance value, there is a possibility of contacting with the flow path forming substrate side due to the thickness of the auxiliary wiring or of discharging to the piezoelectric element, or the like. In order to avoid this, when an interval between the wiring substrate and the flow path forming substrate is increased beyond a certain level, a height of the ink jet recording head is increased, and downsizing cannot be achieved.
These problems are not limited to a piezoelectric device used in a liquid ejecting head such as an ink jet recording head, and are similarly present in the piezoelectric device used in another device.